Is Witr prayer different from the night prayer?

Witr prayer is part of the night prayer, but there is still a
difference between them.

Shaykh Ibn Baaz (may Allaah have mercy on him) said: 

Witr is part of the night prayer, and it is Sunnah and it is
the end of the night prayer, one rak’ah with which one concludes the night
prayers at the end of the night, or in the middle of the night, or at the
beginning of the night after ‘Isha’ prayer. You pray whatever you can, then
you conclude it with one rak’ah. End quote. 

Fataawa Ibn Baaz, 11/309 

Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) said: 

The Sunnah – both in word
and in deed – distinguishes between the night prayers and witr prayer. The
scholars also distinguished between them with regard to the ruling and the
way in which they are done. 

With regard to differentiation made in the Sunnah, according
to the hadeeth of Ibn ‘Umar (may Allaah be pleased with him), a man asked
the Prophet (peace and blessings of Allaah be upon him): How are the
night prayers done? He said: “Two by two, then when you fear that dawn is
about to break, pray Witr with one rak’ah.” Narrated by al-Bukhaari. See
al-Fath, 3/20. 

With regard to the way in which the Prophet (peace and
blessings of Allaah be upon him) differentiated between them in his actions,
according to the hadeeth of ‘Aa’ishah (may Allaah be pleased with her): The
Prophet (peace and blessings of Allaah be upon him) used to pray when I
was lying down across his bed. When he wanted to pray Witr, he would wake me
up and I would pray Witr. Narrated by al-Bukhaari. See al-Fath,
2/487. Also narrated by Muslim (1/51) with the wording: “He used to offer
his prayers at night when I was lying in front of him.” Then when only Witr
was left, he would wake her up and she would pray witr. And Muslim also
narrated (1/508) that she said: The Messenger of Allaah (peace and
blessings of Allaah be upon him) used to pray thirteen rak’ahs at night,
five of which were witr, in which he would not sit except at the end. And he
narrated from her (1/513) that when Sa’d ibn Hishaam said to her: “Tell me
about the Witr of the Messenger of Allaah (peace and blessings of
Allaah be upon him),” she said: “The Prophet (peace and blessings of
Allaah be upon him) used to pray nine rak’ahs during which he would not sit
except in the eighth rak’ah, when he would remember Allaah and praise Him
and call upon Him, then he would get up without saying the salaam, then he
would stand and pray the ninth rak’ah, then he would sit and remember Allaah
(dhikr) and praise Him and call upon Him, then he would say a tasleem that
we could hear.” 

With regard to the way in which the scholars differentiated
between the ruling on witr and the night prayers, the scholars differed as
to whether Witr is obligatory. Abu Haneefah was of the view that it is
obligatory, and this was narrated from Ahmed in al-Insaaf and
al-Furoo’. Ahmad said: Whoever fails to pray Witr deliberately is a bad
man whose testimony should not be accepted. 

The well known view in our madhhab is that witr is Sunnah.
This is the view of Maalik and al-Shaafa’i. 

With regard to the night prayers, there is no such scholarly
dispute. In Fath al-Baari (3/27) it says: I have not seen
anyone narrate the view that it is obligatory except for some of the
Taabi’een. Ibn ‘Abd al-Barr said: Some of the Taabi’een held an odd view and
said that qiyaam al-layl is obligatory, even if it is done only for the
length of time that it takes to milk a sheep. But the view of the majority
of scholars is that it is recommended. End quote. 

With regard to the scholars’ differentiating between the ways
in which witr and the night prayers are done, our Hanbali fuqaha’ have
clearly stated that they are done differently. They said: The night prayers
are done two by two, and they said concerning witr: witr may be prayed with
five, or seven, rak’ahs, in which one does not sit except in the last one.
If a person prays witr with nine rak’ahs, he should sit immediately after
the eighth rak’ah and recite the tashahhud, then he should stand up before
saying the salaam and do the ninth rak’ah, then he should say the tashahhud
and the salaam. This is what was stated by the author of Zaad
al-Mustaqni’. End quote. 

Majmoo’ Fataawa Ibn ‘Uthaymeen,
13/262-264. 

Thus it is clear that witr prayer is part of the night
prayers, but it differs from them in some minor details such as how it is
done. 

And Allaah knows best.